Skip to content

Commit

Permalink
Update README.md
Browse files Browse the repository at this point in the history
  • Loading branch information
fabriziosalmi authored Aug 23, 2024
1 parent 5d35304 commit f412864
Showing 1 changed file with 78 additions and 0 deletions.
78 changes: 78 additions & 0 deletions docs/lxc_model/README.md
Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@
- **[Usage](#usage)**: Instructions on how to start, stop, and manage the LXC AutoScale ML service.
- **[Logging and Outputs](#logging-and-outputs)**: Information on logging and interpreting scaling suggestions.
- **[Error Handling](#error-handling)**: Explanation of the error handling mechanisms implemented in the service.
- **[Autoscaling](#autoscaling)**: Explanation of the autoscaling logic and the role of the machine learning model.
- **[Best Practices and Tips](#best-practices-and-tips)**: Recommendations for optimizing the performance and reliability of LXC AutoScale ML.

---
Expand Down Expand Up @@ -224,6 +225,83 @@ LXC AutoScale ML is designed with robust error handling to ensure continuous ope

If an error occurs while loading data, the service will log the issue but will continue to monitor other containers. This approach ensures that a single failure does not disrupt the entire service.

---

## Autoscaling

The autoscaling logic in this application is designed to dynamically adjust the CPU and RAM resources allocated to each container based on real-time metrics and the detection of anomalous behavior. This section is critical for ensuring that containers operate efficiently, without under-provisioning (which could lead to performance issues) or over-provisioning (which would waste resources).

### **Key Components of Autoscaling:**

1. **Metrics Monitoring:**
- The autoscaling system continuously monitors various performance metrics of each container. These metrics include CPU usage percentage, memory usage in megabytes (MB), and possibly other custom metrics like `cpu_memory_ratio` or `io_ops_per_second`.
- The metrics data is collected in near real-time and is used both for anomaly detection and for making scaling decisions.

2. **Anomaly Detection Trigger:**
- The first line of decision-making in the autoscaling logic is anomaly detection. By identifying unusual patterns in container behavior, the system can preemptively scale resources before standard thresholds (like CPU or RAM usage) are breached.
- If an anomaly is detected (based on the model’s prediction), the system may trigger an immediate scale-up action, as this often indicates an unexpected spike in demand or a potential fault condition.

3. **Threshold-Based Scaling:**
- In addition to anomaly detection, the system uses predefined thresholds to determine when to scale resources.
- **CPU Scaling:** If CPU usage exceeds a specified upper threshold (`cpu_scale_up_threshold`), the system decides to scale up CPU resources. Conversely, if usage falls below a lower threshold (`cpu_scale_down_threshold`), it considers scaling down the CPU.
- **RAM Scaling:** Similarly, if memory usage exceeds the upper threshold (`ram_scale_up_threshold`), RAM resources are scaled up. If usage is below the lower threshold (`ram_scale_down_threshold`), the system considers scaling down the RAM.
- These thresholds are configurable, allowing users to tailor the scaling behavior to their specific workload requirements.

4. **Action Determination:**
- The scaling decision is refined by ensuring that any scaling actions are within the allowed resource limits.
- **Scaling Up:** When scaling up, the system checks that the new resource allocation does not exceed the maximum limits specified (`max_cpu_cores` for CPU and `max_ram_mb` for RAM).
- **Scaling Down:** When scaling down, the system ensures that resources do not drop below the minimum limits (`min_cpu_cores` for CPU and `min_ram_mb` for RAM).
- The final decision is whether to "Scale Up", "Scale Down", or take "No Scaling" action.

5. **Scaling Execution:**
- Once a decision is made, the system sends requests to adjust the container’s resources. This is done through API calls to an external system or service that manages the containers.
- The system includes a retry mechanism to handle transient errors in the API requests, ensuring that scaling actions are reliable.

### **Considerations for Effective Autoscaling:**
- **Customization:** Users should configure the thresholds and limits based on their specific use cases. For example, a high-performance web server might need aggressive scaling policies, while a background processing container might tolerate higher resource utilization before scaling.
- **Anomaly Sensitivity:** The sensitivity of anomaly detection can be adjusted through the model's contamination parameter. A lower contamination level will make the model more sensitive to anomalies, potentially triggering more frequent scale-up actions.
- **Resource Limits:** Users should carefully set the minimum and maximum resource limits to prevent the system from over-provisioning (wasting resources) or under-provisioning (causing performance degradation).
- **Monitoring:** It’s essential to monitor the scaling actions and adjust the configuration as needed based on observed behavior. Logs and metrics should be reviewed regularly to ensure that the autoscaling logic aligns with the application's performance requirements.

### The model

The application leverages an Isolation Forest model, which is a machine learning algorithm specifically designed for anomaly detection. The model is a crucial component of the autoscaling system, as it helps identify when a container's behavior deviates from the norm, potentially indicating the need for scaling.

#### **Key Aspects of the Model:**

1. **Feature Selection:**
- The model only uses numerical features from the dataset, excluding identifiers like `container_id` and `timestamp`. This ensures that the model focuses solely on the metrics that influence container performance, such as CPU and memory usage.
- Users should be aware that the choice of features can significantly impact the model's effectiveness. Including too many irrelevant features could lead to overfitting, while omitting critical metrics might reduce the model's ability to detect anomalies.

2. **Isolation Forest Overview:**
- **Isolation Forest** is an ensemble-based algorithm that isolates observations by randomly selecting a feature and then randomly selecting a split value between the maximum and minimum values of the selected feature. The idea is that anomalies are few and different, so they are easier to isolate.
- The model works by constructing multiple decision trees and calculating the path length of each observation. Shorter paths correspond to anomalies, as they are easier to isolate.

3. **Configurable Parameters:**
- **Contamination (`contamination`)**: This parameter sets the expected proportion of anomalies in the dataset. A lower contamination level makes the model more conservative (i.e., it will classify fewer points as anomalies). Users should adjust this based on the expected frequency of anomalies in their system.
- **Number of Trees (`n_estimators`)**: This parameter controls how many trees are built in the ensemble. More trees generally improve the model's robustness but also increase computational cost.
- **Max Samples (`max_samples`)**: This parameter limits the number of samples to draw from the dataset to train each tree. It helps in controlling overfitting and can be set based on the size of the dataset.
- **Random State (`random_state`)**: This is a seed for the random number generator to ensure reproducibility of the model's results. It’s particularly useful in a production environment where consistency between runs is important.

4. **Pipeline Integration:**
- The model is integrated into a pipeline that includes a `StandardScaler` for data normalization. This step ensures that all features contribute equally to the model by scaling them to have zero mean and unit variance.
- The pipeline approach allows for seamless integration of preprocessing steps and the model, making it easier to manage and extend the model in the future.

5. **Anomaly Prediction:**
- During prediction, the model generates an anomaly score for each container based on the latest metrics. This score is then converted into a confidence level, which represents the certainty that a container is behaving anomalously.
- A high confidence level indicates that the container's behavior is significantly different from the norm, prompting the autoscaling logic to potentially increase resources.

6. **Scalability and Efficiency:**
- The model is designed to be efficient, even with a large number of containers. The use of a limited number of samples (`max_samples`) and decision trees (`n_estimators`) ensures that the model can make predictions in real-time without significant computational overhead.

### **Considerations for Effective Model Use:**
- **Model Training Frequency:** The model should be retrained periodically to adapt to changes in the workload patterns. If the nature of the container's tasks changes over time, the model might need to be retrained more frequently to maintain its accuracy.
- **Feature Engineering:** Users may need to experiment with different sets of features to find the combination that best captures the conditions leading to anomalies. Feature importance can be assessed using various techniques to refine the model.
- **Model Validation:** Before deploying the model in a production environment, it should be validated using historical data to ensure it accurately detects anomalies and does not produce too many false positives or negatives.

By understanding and configuring these aspects, users can ensure that the autoscaling logic and anomaly detection model work effectively to maintain the optimal performance of their containers. Proper tuning and monitoring of the model and scaling logic will help in achieving a balanced system that adapts dynamically to changing workloads.


---

## Best Practices and Tips
Expand Down

0 comments on commit f412864

Please sign in to comment.